Electroweak baryogenesis and new TeV fermions

Abstract

New fermions, strongly coupled to the Standard Model Higgs boson, provide a well motivated extension of the Standard Model (SM). In this work we show that, once new physics at heavier scales is added to stabilize the Higgs potential, such an extension of the SM can strengthen the first order electroweak phase transition and make the electroweak baryogenesis mechanism feasible. We propose a SM extension with TeV Higgsinos, Winos and Binos that satisfy the following properties: a) The electroweak phase transition is strong enough to avoid sphaleron erasure in the broken phase for values of the Higgs mass m H < ∼ 300 GeV; b) It provides large CP-violating currents that lead to the observed baryon asymmetry of the Universe for natural values of the CP-violating phase; c) It also provides a natural Dark Matter candidate that can reproduce the observed dark matter density; d) It is consistent with electroweak precision measurements; e) It may arise from a softly broken supersymmetric theory with an extra (asymptotically free) gauge sector; f ) It may be tested by electron electric dipole moment experiments in the near future.

Sommerfeld corrections to type-II and type-III leptogenesis

“…It is therefore interesting to study if/how the absolute leptogenesis lower bound on M can be evaded. One possibility is a new source of baryogenesis at the weak scale, for example new physics that makes the electroweak phase transition of second order and provides a new source of CP violation [16], a scenario which is already strongly constrained but not yet excluded. The alternative possibility is another heavier baryogenesis mechanism: here the problem is that the baryon asymmetry gets washed out by triplets unless their L-violating interactions are slower than the expansion rate.…”

Beyond MSSM baryogenesis

“…Some recent examples are [14,15,16,17,18]. In most of these works, new particle degrees of freedom which are added to the model modify the EWPT by actively participating in thermal processes.…”

Virtual signatures of dark sectors in Higgs couplings

“…Our model is similar to the bino-higgsino scenario in the minimal supersymmetric standard model (MSSM) [13], except that the couplings are not set by supersymmetry, but free parameters. The singlet-doublet model has received a lot of attention, due to its interesting phenomenology in the context of dark matter [14][15][16][17], baryogenesis [18,19], and observation prospects at colliders [16,20,21]. Besides those virtues, it provides naturally strong renormalizable interactions between the dark fermions and the Higgs boson.…”

“…Dark fermions with large Yukawa couplings as part of a more complete model can therefore be consistent with vacuum stability. Moreover, they might trigger a first-order electroweak phase transition that facilitates electroweak baryogenesis [18,19,42,43]. Since the respective effects of vacuum stabilization on LHC observables strongly depend on the specific UV completion of our model, we do not consider them in our analysis.…”